This invention relates to a window frame for mounting in an opening defined by a framing support structure of a building, the window frame comprising a plurality of elongate frame members connected together at corners of the window frame, each member having an inner surface facing inwardly toward an opposed one of the members and an outer surface opposed to the inner surface for engaging the frame support structure, the inner surface having glazing support members thereon and the outer surface having a nailing strip mounted thereon for extending along the length of the outer surface outwardly therefrom substantially at right angles for attachment to the framing support structure along an edge of the opening.
Window frames of this type are widely used and are generally shipped from the manufacturer in completed construction, sometimes but not always including the glazing.
On site the window frame is inserted into the opening formed in the framing of the building from the outside until the nailing strip which extends outwardly from the outer surface of the window frame engages the outer surface of the building. The nailing strip is then attached to the outer surface by nails or other fasteners to hold the window frame in place.
The nailing strip has a number of disadvantages. Firstly in shipping, the nailing strip projects outwardly from the outermost edge of the window frame and thus is exposed for damage and also increases the dimensions of the window frame thus increasing shipping costs.
Furthermore when the window frame is manufactured from extruded plastics material such as vinyl, the nailing strip is extruded commonly with the window frame lineal and thus also is of course formed from vinyl. The vinyl nailing strip has a tendency to crack if impacted excessively during the nailing process, particularly when frozen.
One proposal to reduce the problems of the nailing strip is shown in U.S. Pat. No. 4,821,472 (Tix) assigned to Plastic Profiles, Inc. and issued on Apr. 18, 1989. This patent shows a nailing strip which has a first portion attached to the outer surface of the window frame member, a second portion defining the planar strip member for nailed attachment to the framing structure of the building and a flexible portion interconnecting the first and second portions allowing the second portion to flex from the erect position at right angles to the outer surface to a transport position lying generally parallel to the outer surface. This movement is obtained by flexing of material of the flexible portion rather than by hinged rotation of two separate sections of the portions. The nailing strip including the two portions and the flexible interconnecting portion are coextruded from a plastics material. In the above patent the window frame is manufactured from wood and the nailing strip from plastics material which is inserted into a slot in the wooden frame. However it could be expected that the window frame could be manufactured from vinyl in extruded form in which case it would be expected that the nailing strip would be coextruded with the vinyl window frame as an integral element.
While the arrangement above to some extent solves the problems of the nailing strip, it does not overcome the problem of cold weather cracking and does not mount the nailing strip to the best advantage for movement between the transport and erect positions.